John Mayer Supports Katy Perry at Grammys After Party, Spends Time With Her Family -- Details

Katy Perry and John Mayer attend Sony Music Entertainment Post-Grammy Reception at The Palm on January 26, 2014 in Los Angeles, California.Credit: Lester Cohen/Getty Images

What a thoughtful plus-one!John Mayer was the perfect date for girlfriend Katy Perry following the 2014 Grammy Awards Sunday night. The 36-year-old supported the "Dark Horse" singer at the Universal Music Group after party at the Ace Hotel in downtown L.A., and fit right in with her family. (Mayer didn't make an appearance at the actual show, as Perry brought her brother as her date.)

"John and Katy were really cute together," an insider told Us Weekly of the special night out. "John had a personal camera he was taking photographs with all night."

The couple of almost two years were joined by Perry's parents, Keith and Mary, and her musician brother David. And although the "Roar" singer lost out to Song of the Year and Best Pop Solo Performance, Mayer made sure to make it a memorable night.

"John had a personal camera slung around his back and was taking photos of everything and everybody tonight," the eyewitness said. At one point, he kissed his fingers and said "beautiful" before capturing a moment between his leading lady and her mom, and later took a snapshot of Keith holding a glass of champagne, the insider added to Us.

"John seemed really comfortable with Katy's parents and her brother too. [He] was really trying to savor every moment of the night with all the photos he took." Toward the end of the night, the pair quickly flipped through the photos together and when Perry saw one she liked she kissed the "Say" singer on the lips. "They're very sweet together!"

Sweet, and attentive. Mayer was a true gentleman during the night. Before and after the pair mingled with actress Anna Kendrick and country singer Kacey Musgraves, he made sure to take extra care of Perry, 29. He held the back of her dress each time she walked up and down the stairs, the insider noted.